Biophysical interactions in tropical agroforestry systems

sequential systems, simultaneous systems Abstract. The rate and extent to which biophysical resources are captured and utilized by the components of an agroforestry system are determined by the nature and intensity of interac-tions between the components. The net effect of these interactions is often determined by the influence of the tree component on the other component(s) and/or on the overall system, and is expressed in terms of such quantifiable responses as soil fertility changes, microclimate modification, resource (water, nutrients, and light) availability and utilization, pest and disease incidence, and allelopathy. The paper reviews such manifestations of biophysical interactions in major simultaneous (e.g., hedgerow intercropping and trees on croplands) and sequential (e.g., planted tree fallows) agroforestry systems. In hedgerow intercropping (HI), the hedge/crop interactions are dominated by soil fertility improvement and competition for growth resources. Higher crop yields in HI than in sole cropping are noted mostly in inherently fertile soils in humid and subhumid tropics, and are caused by large fertility improvement relative to the effects of competition. But, yield increases are rare in semiarid tropics and infertile acid soils because fertility improvement does not offse

Degradation of haloaromatic compounds

An ever increasing number of halogenated organic compounds has been produced by industry in the last few decades. These compounds are employed as biocides, for synthetic polymers, as solvents, and as synthetic intermediates. Production figures are often incomplete, and total production has frequently to be extrapolated from estimates for individual countries. Compounds of this type as a rule are highly persistent against biodegradation and belong, as "recalcitrant" chemicals, to the class of so-called xenobiotics. This term is used to characterise chemical substances which have no or limited structural analogy to natural compounds for which degradation pathways have evolved over billions of years. Xenobiotics frequently have some common features. e.g. high octanol/water partitioning coefficients and low water solubility which makes for a high accumulation ratio in the biosphere (bioaccumulation potential). Recalcitrant compounds therefore are found accumulated in mammals, especially in fat tissue, animal milk supplies and also in human milk. Highly sophisticated analytical techniques have been developed for the detection of organochlorines at the trace and ultratrace level

Labor- und Feldversuche zur mikrobiologischen Sanierung von altoelkontaminierten Raffineriestandorten Endbericht

To develop techniques for the microbial on-site (pile) and in-situ reclamation, laboratory and pilot-scale experiments were performed at a contaminated former waste oil refinery site. Concerning the pile experiments, volatile pollutants like chlorinated hydrocarbons and benzene derivatives (BTEX) were stripped almost completely during excavation and soil preparation. The concentrations of lower molecular mass polychlorinated hydrocarbons (PCB) were reduced by about 50% during a pile treatment of more than 1 year. The mineral oil hydrocarbons were reduced by about 70% independent from methods and starting concentrations. The remaining fraction was of high molecular mass, not leachable and not bioavailable. For the microbiological in-situ remediation of saturated aquifers, an optimal oxygen supply of microorganisms is of greatest importance. The electron acceptors tested were hydrogen peroxide (H_2O_2), technical grade oxygen (O_2), and nitrate. H_2O_2 was recommended: it provides the best O_2 supply and caused the highest microbial degradation activity. Nitrate can be applied additionally. Due to a lower mineralisation efficiency compared to H_2O_2, it results in a 'pre-remediation' of the anaerobic areas of the aquifer. Chlorinated hydrocarbons and BTEX were preferentially washed out hydraulically. The result of R and D project were directly transferred into execution plans for the microbial on-site and in-situ remediation at the site. Due to a high H_2O_2 decay and a resulting formation of O_2 bubbles in the aquifer, the technical reclamation will include a pulsed infiltration. A monitoring program was elaborated for the control and optimisation of the in-situ remediation. (orig.)Available from TIB Hannover: F95B2542+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany); Hessische Industriemuell GmbH, Wiesbaden (Germany). Bereich AltlastensanierungsgesellschaftDEGerman

Mikrobielle Sanierung von TNT-kontaminierten Boeden des Standortes Hessisch Lichtenau im Rahmen des Verbundforschungsprojektes Ruestungsaltlasten. Teilvorhaben 2 Endbericht

SIGLEAvailable from TIB Hannover: F96B98+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Bewertung von organisch-chemischen Stoffen Besprechungsprotokoll

TIB: D.Dt.F./AC 1000 (15,78) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Erarbeitung von Programmen zur Ueberwachung von altlastverdaechtigen Flaechen und Altlasten. Bd. 1 und 2

At present, the monitoring of contaminated sites in the Federal States of Germany is managed in different ways: The aim of the research project was to formulate minimum demands for monitoring programmes on the basis of the German Federal Soil Protection Act (Bundes-Bodenschutzgesetz). The technological basis was developed and discussed in detail and model monitoring programmes were derived for volatile halogenated hydrocarbons, mineral oil hydrocarbons, aromatic hydrocarbons, polycyclic aromatic hydrocarbons, heavy metals, contaminated sites with domestic waste and a complex site with different groups of contaminants. It is demonstrated in four case examples that these models can be used in practice. (orig.)Published in two volumesAvailable from TIB Hannover: RN 8422(1999,96,1): RN 8422(1999,96,2) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Umwelt, Naturschutz und Reaktorsicherheit, Bonn (Germany)DEGerman

Ermittlung und Bewertung der Umweltbelastung und -verteilung von Verbrauchschemikalien Beispiel: p-Dichlorbenzol als Geruchsuebertoener im Sanitaerbereich. Abschlussdatum: Dezember 1981

TIB: RN 8908 (81-120) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman